The invention generally relates to controlling the proper function of a microprocessor or a microcontroller of a computer, notably on board a vehicle. An effect of the invention is thus to provide a device for controlling the reinitialization of a computer, particularly meant for automotive vehicles.
It is known that an automotive vehicle comprises a plurality of functional devices controlled by a command device, called a computer. Such a computer allows the command of the vehicle's lights (brake lights, turn signals, etc.) or the commands of the front and back windshield wipers to be activated, for example.
In reference to FIG. 1, a computer comprises a command module, comprising a microcontroller or a microprocessor, ensuring a plurality of functions allowing functional devices of the vehicle to be controlled. Based on the context (luminosity, temperature, etc.), these functions are in an active or inactive state. However, as is known, such a computer may sometimes have malfunctions.
According to the prior art, a monitoring device, commonly known as a “watchdog,” may be integrated into the computer to monitor its proper state of function. FR 2770917 describes a control system of a vehicle computer comprising a monitoring device. Such a monitoring device allows the operating state of the functions of the command module of the computer to be monitored. The control system described in FR 2770917 furthermore comprises means for reinitializing all of the functions of the command module in case a malfunction is detected.
Such a monitoring device typically functions by transmitting a signal which is periodically issued by the command module, allowing a timer to be regularly rearmed. When an action of the command module takes too long to be performed, the signal is not sent and the timer continues its countdown until the end. The monitoring device then commands an automatic reinitialization of the computer when the signal is no longer sent and the timer is not rearmed.
During the reinitialization of the computer, some of the aforementioned functions of the command module must be conserved or placed in a defined state with an aim to ensure the safety of the vehicle passengers and/or not to disturb the driver, while other functions may be interrupted. It is then known to differentiate between so-called “maintained” functions, when the corresponding function must be controlled within a precise output state—active, inactive or any other value, or remain in an unchanged state—during the reinitialization of the computer, and so-called “interruptible” functions, when the corresponding function can be deactivated, regardless of its state (active, inactive or any other value) during the reinitialization of the computer. In other words, functions “maintained” during reinitialization refer to functions having to be controlled, namely forced into a state, active, inactive or any other value, or unchanged, i.e. maintained in a state identical to the state before reinitialization. “Interruptible” functions refer to functions which can be interrupted during reinitialization, i.e. whose output state is of little importance during reinitialization.
As non-limiting examples, functions having to be maintained, i.e. controlled in an output state, during the reinitialization of the computer, correspond to the running lights of the vehicle, which must remain active in case of operation in nighttime conditions, or even the car horn which, on the other hand, must be kept in an inactive state throughout reinitialization.
However, this maintenance of functions maintained in a controlled state (active, inactive or any other value) or unchanged during the reinitialization phase may require the use of additional electronic components. In particular for each of the functions maintained in an unchanged state, it is known to use, for example, a demultiplexer comprising a storage module, known as a “latch.” Such a demultiplexer commands the signals dispatched by the functions of the command module and spreads them along the paths for which they are meant (maintained active or inactive, for example). In other words, such a set of demultiplexers allows the output states of the functions maintained to be sorted, between those maintained active, those maintained inactive and those maintained unchanged. Furthermore, the latch allows the storage of this output state of the maintained functions requested by the command module.
Such a “watchdog” monitoring device thus comprises a latch for each of the functions having to be forced or maintained in an unchanged state, which presents the disadvantage of using a large number of electronic components. Moreover, such a computer, comprising so many components, presents a high cost.